Small-size light-weight transformer with new core structure for contactless electric vehicle power transfer system

A contactless power transfer system for electric vehicles is required to have high efficiency, a large air gap, good tolerance to misalignment in the lateral direction, and be compact and lightweight. A new 1.5 kW transformer has been developed to satisfy these criteria using novel H-shaped cores, which is more efficient, more robust to misalignment, and lighter than previously employed rectangular cores, and its characteristics are described. An efficiency of 95% was achieved across a 70 mm air gap. The results of test at wide air gap of 100 mm, temperature rise test and 3 kW operation test are also presented.